The present invention relates to a synchronizer ring in a vehicle speed change gear, especially in a synchronizing speed change gear.
The synchronizing speed change gear is provided with a synchronizer ring axially movable between a gear and a connecting sleeve, and synchronizes the circumferential speed of the both before gearing the connecting sleeve and the gear.
A Warner type of the synchronizer ring has a spline on an outer diameter part thereof and a conical surface on an inner diameter part, which engages by friction a conical surface of the gear. On the other hand, a pin type of the synchronizer ring is reversed in positions of the conical surface of the gear and the radius direction of the spline, and the other diameter part is formed with the conical surface for friction-gearing the conical surface of the synchronizing outer ring of the gear.
With respect to the synchronizer ring, a special high tension brass has been conventionally employed for blank material, and forged to form spline and a conical surface, and processed on the conical surface with grooves of fine and high precision. Unfortunately, the blank material is expensive and difficult to process, and the production cost is very high at low productivity. There is another synchronizer ring where the whole body is made of a ferrous metal and the conical surface is coated with molybdenum. This structure is also unavoidably expensive in the production cost.
For use, when the mutual slidings are large or when difference in mutual rotations is large, the above mentioned former special high tension brass causes plastic flow due to friction heat in addition to scratch abrasion. The latter ferrous metal causes defects by attacking, shocks and others, since the abrasion resistibility of the molybdenum layer is too high for the conical surface of the gear. Therefore, the synchronizing durability is poor, and especially as low viscosity of the gear oil and high power of the engine have advanced nowadays, the abrasion of the conical surface has been severe and the above said inconvenience has been accelerated, accordingly.
There is a further synchronizer ring where the conical surface of the ring body is applied with fibrous (porous) paper material. However in this synchronizer ring, the paper material fabricating the friction surface and the ring body are independently manufactured, and after then they are combined. Therefore, the undermentioned defects appear.
For manufacture, this ring requires processes of; preparing a sheet paper material by adhering friction increasing powders such as red oxide of iron, calcium carbonate or the like to the cellulose fiber; cutting such a treated sheet paper to form a determined lining shape (ring shape); making the conical surface of the ring body on which the adhering agent is coated; pressing and adhering the ring shaped paper material; and grinding this adhered paper material. As is seen, many processing steps are involved in manufacturing, so that this kind of synchronizer ring is also expensive.
In view of the facility, the production requires a means of dispersing the cellulose fiber in the water at a determined density, a hot blast stove, a process from the sheet paper base to the lining material, a roll for adhering it to the ring body, and pressure. These steps invite the high cost, too.
Further, the paper material is adhered to the ring body where the paper material is separately prepared, and securing force is much unbalanced due to quality and quantity of the used binder and the observation of its thickness is difficult. The lubricant goes between the paper material and the ring body because of porosity of the paper. Particularly, if the lubricant were heated at the high temperature or the product were used in the geographical hot field, the paper material would be exfoliated. Besides, the paper material is expanded by adhering the lubricant so that it bites the conical surface of the object when synchronization is finished. Since the paper material is weak in strength, it easily invites pitching abrasion by shock. The connical surface of the paper material becomes carbonized by using it for a long period of time, and the friction coefficient becomes changed at the starting time. Because of these causes, stabilization of the synchronization is poor and the operation is not smooth.